A game limit makes it harder for new players to get games under their belt. For a returning pro it would be hard to qualify for PO.
I totally understand the concern about them not having enough people to play though, so maybe you could allow returning players to request their restrictions to be lifted after reaching a certain amount of games/points.
Could be actually automatic, like this way:
If a player has played 50 games or less overall, his seasonal game limit is 5 games per player. Once he has played 50 games overall, his game limit is normal 15 games per player. The new player would need to play at least 9 more opponents during his 1st season before he could play against the 1st noob-basher again. After 50 games it should be less rewarding to bash him more.
Combine that with lower base points for the first 10 games or so in each scheme and the noob-bashing days are gone